/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkData_DEFINED
#define SkData_DEFINED

#include "include/core/SkRefCnt.h"
#include "include/private/base/SkAPI.h"
#include "include/private/base/SkAssert.h"

#include <cstdint>
#include <cstdio>

class SkStream;

/* *
 * SkData holds an immutable data buffer. Not only is the data immutable,
 * but the actual ptr that is returned (by data() or bytes()) is guaranteed
 * to always be the same for the life of this instance.
 */
class SK_API SkData final : public SkNVRefCnt<SkData> {
public:
    /* *
     * Returns the number of bytes stored.
     */
    size_t size() const
    {
        return fSize;
    }

    bool isEmpty() const
    {
        return 0 == fSize;
    }

    /* *
     * Returns the ptr to the data.
     */
    const void *data() const
    {
        return fPtr;
    }

    /* *
     * Like data(), returns a read-only ptr into the data, but in this case
     * it is cast to uint8_t*, to make it easy to add an offset to it.
     */
    const uint8_t *bytes() const
    {
        return reinterpret_cast<const uint8_t *>(fPtr);
    }

    /* *
     * USE WITH CAUTION.
     * This call will assert that the refcnt is 1, as a precaution against modifying the
     * contents when another client/thread has access to the data.
     */
    void *writable_data()
    {
        if (fSize) {
            // only assert we're unique if we're not empty
            SkASSERT(this->unique());
        }
        return const_cast<void *>(fPtr);
    }

    /* *
     * Helper to copy a range of the data into a caller-provided buffer.
     * Returns the actual number of bytes copied, after clamping offset and
     * length to the size of the data. If buffer is NULL, it is ignored, and
     * only the computed number of bytes is returned.
     */
    size_t copyRange(size_t offset, size_t length, void *buffer) const;

    /* *
     * Returns true if these two objects have the same length and contents,
     * effectively returning 0 == memcmp(...)
     */
    bool equals(const SkData *other) const;

    /* *
     * Function that, if provided, will be called when the SkData goes out
     * of scope, allowing for custom allocation/freeing of the data's contents.
     */
    typedef void (*ReleaseProc)(const void *ptr, void *context);

    /* *
     * Create a new dataref by copying the specified data
     */
    static sk_sp<SkData> MakeWithCopy(const void *data, size_t length);


    /* *
     * Create a new data with uninitialized contents. The caller should call writable_data()
     * to write into the buffer, but this must be done before another ref() is made.
     */
    static sk_sp<SkData> MakeUninitialized(size_t length);

    /* *
     * Create a new data with zero-initialized contents. The caller should call writable_data()
     * to write into the buffer, but this must be done before another ref() is made.
     */
    static sk_sp<SkData> MakeZeroInitialized(size_t length);

    /* *
     * Create a new dataref by copying the specified c-string
     * (a null-terminated array of bytes). The returned SkData will have size()
     * equal to strlen(cstr) + 1. If cstr is NULL, it will be treated the same
     * as "".
     */
    static sk_sp<SkData> MakeWithCString(const char cstr[]);

    /* *
     * Create a new dataref, taking the ptr as is, and using the
     * releaseproc to free it. The proc may be NULL.
     */
    static sk_sp<SkData> MakeWithProc(const void *ptr, size_t length, ReleaseProc proc, void *ctx);

    /* *
     * Call this when the data parameter is already const and will outlive the lifetime of the
     * SkData. Suitable for with const globals.
     */
    static sk_sp<SkData> MakeWithoutCopy(const void *data, size_t length)
    {
        return MakeWithProc(data, length, NoopReleaseProc, nullptr);
    }

    /* *
     * Create a new dataref from a pointer allocated by malloc. The Data object
     * takes ownership of that allocation, and will handling calling sk_free.
     */
    static sk_sp<SkData> MakeFromMalloc(const void *data, size_t length);

    /* *
     * Create a new dataref the file with the specified path.
     * If the file cannot be opened, this returns NULL.
     */
    static sk_sp<SkData> MakeFromFileName(const char path[]);

    /* *
     * Create a new dataref from a stdio FILE.
     * This does not take ownership of the FILE, nor close it.
     * The caller is free to close the FILE at its convenience.
     * The FILE must be open for reading only.
     * Returns NULL on failure.
     */
    static sk_sp<SkData> MakeFromFILE(FILE *f);

    /* *
     * Create a new dataref from a file descriptor.
     * This does not take ownership of the file descriptor, nor close it.
     * The caller is free to close the file descriptor at its convenience.
     * The file descriptor must be open for reading only.
     * Returns NULL on failure.
     */
    static sk_sp<SkData> MakeFromFD(int fd);

    /* *
     * Attempt to read size bytes into a SkData. If the read succeeds, return the data,
     * else return NULL. Either way the stream's cursor may have been changed as a result
     * of calling read().
     */
    static sk_sp<SkData> MakeFromStream(SkStream *, size_t size);

    /* *
     * Create a new dataref using a subset of the data in the specified
     * src dataref.
     */
    static sk_sp<SkData> MakeSubset(const SkData *src, size_t offset, size_t length);

    /* *
     * Returns a new empty dataref (or a reference to a shared empty dataref).
     * New or shared, the caller must see that unref() is eventually called.
     */
    static sk_sp<SkData> MakeEmpty();

private:
    friend class SkNVRefCnt<SkData>;
    ReleaseProc fReleaseProc;
    void *fReleaseProcContext;
    const void *fPtr;
    size_t fSize;

    SkData(const void *ptr, size_t size, ReleaseProc, void *context);
    explicit SkData(size_t size); // inplace new/delete
    ~SkData();

    // Ensure the unsized delete is called.
    void operator delete(void *p);

    // shared internal factory
    static sk_sp<SkData> PrivateNewWithCopy(const void *srcOrNull, size_t length);

    static void NoopReleaseProc(const void *, void *); // {}

    using INHERITED = SkRefCnt;
};

#endif
